Anti-friction bearings, such as ball or roller bearings, require lubrication to ensure proper operation. Often these bearings are mounted in remote or inaccessible locations where it is difficult to deliver an adequate supply of lubricant to the bearings. One known method of lubricating these remotely positioned bearings is to fill or pack them with grease prior to operating the device in which the bearings are installed. Since the grease has a tendency to flow out of the bearings during operation of the device, assemblies employing grease packed bearings usually incorporate seals mounted either directly on or adjacent to the bearings to retain the grease.
A problem sometimes encountered with bearings lubricated in the manner described above is that since the grease is retained in the bearings, it tends to degrade over prolonged periods of operation. This degradation can result in a decrease in grease viscosity and a concomitant increase in the operating temperature of the bearings. If this problem is not addressed by re-packing the bearings with fresh grease, the existing grease will continue to degrade and ultimately cause the bearings to overheat and fail. However, due to the aforementioned seals, re-packing the bearings with fresh grease can require that the bearing assembly be dismantled and the seals removed to gain access to the bearings.
Another problem associated with known grease-lubricated bearing assemblies is that in most rolling element bearings some metal-to-metal contact occurs between the rolling elements and the bearing races. This metal-to-metal contact results in the production of debris in the form of metal particles, a phenomena known to those skilled in the art as fretting. If these metal particles are not flushed from the bearings they can become lodged between the balls or rollers and the bearing races further exacerbating the fretting problem and increasing the likelihood of bearing failure. Accordingly, lubricant should be fed through the bearings at least occasionally to flush out the contaminants. However, when the grease is retained in the bearings by the seals, there is no mechanism for doing this.
Still another difficulty occurs when rolling element bearings are employed in high speed applications. In these situations, the centrifugal forces exerted by the rolling elements of the bearings on the outer bearing races can be quite high. This in turn causes an increase in bearing friction and hence bearing temperature which accelerates the deleterious effects of the problems described above. Where the bearings are eccentrically mounted to a rotating member for rotation relative thereto, the component of centrifugal force imparted by the rotating member to which the bearings are mounted is combined with the centrifugal forces generated due to the bearings own high rate of rotation, further exacerbating the difficulties described herein. This situation is often encountered in reciprocating knife cutting heads on cloth cutting machines where the knife is reciprocated by direct or indirect connection to a drive member eccentrically rotatably supported on a flywheel or other crank member.
Based on the foregoing, it is the general object of the present invention to provide a bearing lubrication delivery mechanism that overcomes the above-described drawbacks of prior art lubrication methods.
It is a further object of the present invention to provide a self-contained bearing lubrication delivery mechanism whereby bearings that are generally inaccessible during operation of the device in which they are installed, can be presented with fresh lubricant.